When considering the indigenous deep-seated mycoses, candidiasis, cryptococcosis, aspergillosis and mucormycosis, as being ‘modern’, one should keep in mind that most of them were fully described a 100 and more years ago, just before bacterial (and subsequently, viral) infections were discovered. At that time the mycoses, being less frequent and by far less important, fell almost entirely into oblivion. In the course of the last 2 or 3 decades, they regained interest since many bacterial and even viral diseases were brought under control and there was a real increase in incidences owing to modern, mostly iatrogenic predispositions such as leukemia treated with cytostatics, immunosuppression, prolonged survival of severely burned patients, use of indwelling intravascular catheters, open-heart surgery and chemotherapy with antibacterial antibiotics. Nowadays, most of the mycoses in question are in fact secondary in nature but the same is true for an increasing number of bacterial and viral diseases, whereas the proportion of the ‘classical’, primary infectious diseases has become comparatively small in developed countries. The diagnosis of deep-seated mycosis must often be considered as an alternative to that of bacterial or viral disease, and therefore, medical mycology should be integrated into the routine of the institutes of medical microbiology.